Type II–type I conversion of GaAs/GaAsSb heterostructure energy spectrum under optical pumping

Morozov, S. V.; Kryzhkov, D. I.; Yablonsky, A. N.; Антонов, А. В.; Kuritsin, D I; Гапонова, Д. М.; Sadofyev, Yu. G.; Samal, N.; Гавриленко, В. И.; Krasilnik, Z. F.

doi:10.1063/1.4802500

Cited by 17 publications

(8 citation statements)

References 18 publications

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“…Since this heterojunction between 2D and 3D phases inhibits charge recombination, we assume that the crystallographic connectivity between the two phases is good, without a significant density of crystal defects, and hence presents a clean electronic interface. Since the band gaps of the layered perovskite phases are wider than the band gap of the 3D phases 37 , the electronic configuration across the 2D-3D heterojunction will be similar to a classical type-I or type-II heterojunction 38 . We illustrate such a type-I configuration in Fig.…”

Section: Resultsmentioning

confidence: 99%

Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites

et al. 2017

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Three-dimensional (3D) organic-inorganic perovskite solar cells have undergone a meteoric rise in cell efficiency to > 22%. However, the perovskite absorber layer is prone to degradation in water, oxygen and UV light. Two-dimensional (2D) Ruddlesden−Popper layered perovskites have exhibited promising environmental stability, but perform less well in solar cells, possibly due to the inhibition of out-of-plane charge transport by the insulating spacer cations. Alternatively, moving away from methylammonium, to the mixed cation formamidinium-caesium based perovskites has led to considerably enhancement of the stability of 3D perovskite absorber layers. Here, we report highly efficient and stable perovskite solar cells based on a self-assembled butylammonium-Cs-formamidinium mixed-cation lead mixed-halide perovskite photoactive layer. Long-chain alkyl-ammonium halides added to the formamidinium-cesium based perovskite precursor solution strongly enhances the crystallinity of the 3D perovskite phase, while also inducing the formation of new layered-phases in the films. By carefully regulating the composition, we are able to achieve "plate-like" layered perovskite crystallites standing up between the host 3D perovskite grains. This spontaneously forming heterostructure allows the efficient charge carrier transport in the 3D perovskite phase, while reducing charge recombination via fortuitous grain boundary passivation. We also observe reduced current-voltage hysteresis and improved device stability, which we correlate to enhanced crystallinity and reduced crystal defects in the 3D perovskite phase. With the optimized composition, we achieved a power conversion efficiency of 20.6% (stabilised efficiency of 19.5%) from a narrow bandgap (1.61 eV) perovskite solar cell and of 17.2 % (stabilised efficiency of 17.3%) from a wider bandgap (1.72 eV) perovskite solar cell optimised for tandem applications. In addition to enhanced efficiency, the addition of butylammonium greatly enhances the long-term stability of the devices. For the first time, our cells sustain more than 80% of their "post burn-in" efficiency after 1,000 hrs of aging under simulated full spectrum sun light measured in an ambient environment without encapsulation. With additional sealing with a glass/polymer-foil/glass laminate, we extend this lifetime to close to 4,000 hrs. Our work illustrates that engineering heterostructures between 2D and 3D perovskite phases is both possible, and can lead to enhancement of both performance and stability of perovskite solar cells.

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Section: Resultsmentioning

confidence: 99%

Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites

et al. 2017

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“…For ternary alloys, the bandgap of the material will be influenced by the composition, and the band structure of the heterojunction is affected by the band alignment of the materials. As pointed out by researchers, 16 the GaAs/GaAsSb quantum well can form a type-I band alignment at the lower Sb mole fractions and a type-II band alignment when the Sb composition is high.…”

mentioning

confidence: 83%

Optical properties of quasi-type-II structure in GaAs/GaAsSb/GaAs coaxial single quantum-well nanowires

Tang

Kang

et al. 2018

Applied Physics Letters

117

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The GaAsSb-based quantum well plays a very important role in optoelectronic devices due to its excellent wavelength tunability. When the dimension reduces, the quantum confinement effect will take place and the quantum well in nanowires will show many interesting characteristics. GaAsSbbased quantum-well nanowires are of contemporary interest. However, the properties of the quasitype-II structure in a single quantum well nanowire have been rarely investigated. Here, we grow GaAs/GaAs 0.92 Sb 0.08 /GaAs coaxial single quantum-well nanowires and discussed their powerdependent and temperature-dependent photoluminescence. We find that due to the small band offset of conduction bands, both type-I like and type-II like emission exist in our nanowires. When electrons obtain enough thermal energy through collisions or surrounding environment, they will overcome the barrier and diffuse to the GaAs conduction band, which contributes to the type-II like recombination. These results show the optical property of the quasi-type-II quantum well in nanowires, which can pave the way toward future nanoscale quantum well devices. Published by AIP Publishing.

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“…To determine the type of band configuration by PL measurement, photoexcited carrier densities of electrons and holes must be enough small to keep the flat band and also a sample must be at low temperature not to detect photons from the inner layer transition between thermally excited electron and holes. Actually the type II to type I transition was observed in GaAs/GaAsSb system with increasing photoexcitation power [22,23]. On the other hand, there are reports which interpret that luminescence from a single GaAsBi/GaAs QW consists of lower energy photons due to localized electron hole pairs and higher energy photons from the band edge transition [24,25].…”

Section: IIImentioning

confidence: 96%

Growth of GaAsBi/GaAs Multi Quantum Wells on (100) GaAs Substrates by Molecular Beam Epitaxy

Pallavi

Tatebe

Nabara

et al. 2015

e-J. Surf. Sci. Nanotech.

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Multi-quantum wells (MQWs) consisting of 3 or 3.5 pairs of nominally 8.8-nm-thick GaAs layers and 5.6-nmthick GaAs0.97Bi0.03 were grown by molecular beam epitaxy with varying the growth temperature of GaAs layers, TGaAs, and keeping the growth temperature of the GaAsBi layers at 350• C and their Bi compositional structure and optical properties were investigated. Analysis of x-ray diffraction spectra reveals that 67% of the total Bi atoms supplied during growth of a single GaAsBi layer were segregated on the growing surface and were incorporated into the successive GaAs layer at TGaAs = 350• C. The GaAs layers at TGaAs = 450 and 500• C contained 17% of the Bi atoms totally supplied and 50% of them were evaporated. Almost all Bi atoms segregated during growth of GaAsBi evaporated and were not incorporated into the GaAs layer at TGaAs = 550• C or higher. Photoluminescence (PL) spectra at 13 K shows all MQW samples have good optical quality and the MQW sample grown at TGaAs = 550• C shows the longest wavelength emission peak at 1116 nm which is 44 nm longer than the PL wavelength for the MQW grown at TGaAs = 350• C, even though the tremendous reduction of Bi incorporation into the GaAs layer grown at TGaAs = 550• C. The result strongly suggests that GaAsBi/GaAs has the type II band configuration.

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Type II–type I conversion of GaAs/GaAsSb heterostructure energy spectrum under optical pumping

Cited by 17 publications

References 18 publications

Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites

Efficient ambient-air-stable solar cells with 2D–3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites

Optical properties of quasi-type-II structure in GaAs/GaAsSb/GaAs coaxial single quantum-well nanowires

Growth of GaAsBi/GaAs Multi Quantum Wells on (100) GaAs Substrates by Molecular Beam Epitaxy

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